This invention relates generally to an expendable jaw system for use in connection with lathes, milling machines and other machines which rotatably work stock or work pieces through cutting or other machining operations.
In machining operations, lathes, milling machines, or the like are used to cut, grind, or otherwise shape stock or work pieces. These machines generally use a chuck in order to hold the work piece during the machining operations.
Chucks typically include three or four jaws which move radially inwardly and outwardly with respect to a central, axial passage provided in the chuck for receiving the raw stock or work piece. Movement of the jaws, sometimes referred to as xe2x80x9cmaster jaws,xe2x80x9d may be performed dependently or independently with respect to one another, and the jaws are ordinarily attached to mechanical or hydraulic means and move within channels provided in the chuck. In many instances, these channels have an inverted T-shape for receiving and securing jaw nuts to which top jaws, also referred to as xe2x80x9csoft jaws,xe2x80x9d are attached.
The top jaws may be attached to the master jaws in a variety of ways, but perhaps the most common means is through use of serrated rails or tracks, which are provided on the master jaws and which mate with corresponding serrations on the bottom of the top jaws. The top jaws are positioned radially inwardly or outwardly at the desired location on the master jaw, and are then bolted into place using bolts which engage the jaw nuts to securely hold the top jaw in place.
The top, or soft, jaws are positioned on the master jaw such that as the master jaws move inwardly, the extreme ends of the top jaws on the chuck approach one another and are configured to grip the work piece therebetween. Because the ends of the top jaws may themselves require boring or other machining to accommodate and hold the work piece, the top jaws may find limited, or even one-time use for clamping a particular work piece for a production run of such work pieces. Thereafter, the top jaws may no longer be practical for use and are thus subsequently discarded.
Because of the provision of serrations on the bottom of such top jaws, their cost of manufacture is significant, and it would be desirable to have top jaws which could be re-used more frequently and/or which are less costly to manufacture. Moreover, it would be desirable to provide a top jaw design which could be readily made from conventional bar stock or other material generally found on-hand in machine shops.
Numerous jaw configurations have been patented. For example, U.S. Pat. No. 4,772,034, issued to Brown, discloses a soft jaw system having a lock ring with studs and nuts for adjusting the soft jaws. U.S. Pat. No. 5,236,207, issued to Ramunas, et al, discloses a segmented adjustable top jaw having a slot for allowing variable gripping forces.
U.S. Pat. No. 5,735,534, issued to Edwards, discloses a top jaw having a recessed slot for receiving a locking ridge of a mounting base, the mounting base including tracks received by rails of the top jaw.
U.S. Pat. No. 4,706,973, issued to Covarrubias, et al, and U.S. Pat. No. 5,542,686, issued to Revuelta, also disclose other chuck-gripping arrangements. Further, U.S. Pat. No. 5,842,704, issued to Gilliam, discloses quick-change jaw inserts for use in connection with a chuck.
Apparently, some form of reusable top jaws with expendable soft jaw inserts are offered for sale by HandS Machine Works of Kent, Wash.
While the foregoing designs are known, there still exists a need for an expendable jaw system which is versatile in its application and allows for use of readily available, standard materials for manufacture of expendable components.
It is, therefore, the principal object of this invention to provide a jaw system having expendable jaw members.
It is another object of the present invention to provide a jaw system having a receiver, or pocket, member for attachment to a jaw of a chuck and a jaw insert for receipt in the pocket member.
A further object of the present invention is to provide an expendable jaw member which is relatively simple to manufacture from readily available stock materials.
Another object of the present invention is to provide jaw members of a variety of configurations for use in gripping work pieces of various shapes.
Yet another object of the present invention is to provide a pocket member and jaw insert member, wherein the pocket member can be configured for use on a variety of different chuck configurations.
A still further object of the present invention is to provide multiple jaw insert members for use in connection with the pocket member in order to maximize the life and/or length of the jaw insert.
A still further object of the present invention is to provide adjustment means for precise adjustment of a jaw insert with respect to the pocket member.
A further object of the present invention is to provide a method of gripping a work piece in a chuck system.
Generally, the present invention includes a jaw system for use in connection with a chuck for a lathe, milling machine, or the like used to hold stock being worked, and includes a receiver, or pocket, member for attachment to the chuck and an engagement member for engaging the stock. The engagement member is attached to the receiver member, and the receiver member defines a longitudinally-extending recess for receipt of the engagement member. A locking means is provided for selectively locking the engagement member to the receiver member.
More specifically, the receiver member is attached to a master jaw of the chuck and, in one preferred embodiment, includes an elongated slot which allows some flexibility in the positioning of the receiver member with respect to the master jaw. The engagement member, or jaw insert, is received within the recess, or pocket, of the pocket member. The jaw insert member is preferably constructed of mild steel and is bar stock of the dimensions of conventional, readily available raw bar stock. The jaw insert member is designed to be sacrificial and expendable. However, because of its relative simplicity and low cost, the benefits are of more expensive, soft jaws are obtained, without the additional cost.
The pocket member is preferably constructed of durable material, such as tool steel, and, since the pocket member does not actually grip the work piece during machining, allows for continued reuse. As compared to the jaw insert, the pocket member is of more complex manufacture and cost, but may only require a single purchase, with the expendable portion of the jaw system, namely, the jaw insert, being replaceable at low cost and of relatively simple manufacture.
The jaw system of the present invention also allows for precise adjustment, or extension, of the jaw insert from the pocket member through use of unique adjustment screws. An adjustment screw can be provided in the pocket member for adjusting the position of the jaw insert with respect to the pocket member, or, alternately, the adjustment screw could be provided in the insert itself for achieving such adjustment. Additionally, a spacer member is disclosed which can be used in conjunction with an adjustment screw to gain further extension of a jaw insert from a pocket member, for perhaps reaching parts of small diameters, and for prolonging the usable life of the jaw insert.
The present invention also discloses a method of holding stock or a work piece during machining using an expendable jaw system as set forth herein.